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APAP|365 > Action > Advocacy > White Spaces

White Spaces and Wireless Microphones 

In Brief

For the past three decades, wireless microphone users including performing arts organizations, academic institutions, touring organizations, individual artists, and audio services contractors have utilized wireless equipment operating within the “white space” radio frequencies between broadcast channels of the broadcast spectrum. In order to avoid radio interference to professional wireless microphone and audio systems, as well as new white space devices, these class of users must be licensed under a Part 74 license classification.

APAP|Public Affairs has been advocating for the legitimate and protected use of wireless microphones on behalf of its members before the FCC. The decisions reached in the White Spaces Order reflect improvements from the original nature of the proceeding and compromises in favor of performance organizations. During this process, we are grateful for the support of the law firm of Holland & Knight. Attorneys in its Communications Practice are prepared to assist APAP members in understanding FCC requirements, managing wireless microphones, registering uses of them, and if necessary, requesting waivers.

Advocacy and Leadership on the White Spaces Issue for the Performing Arts


In its recent decision (September 23, 2010) on broadcast television spectrum "White Spaces," the Federal Communications Commission ("FCC") adopted rules and procedures which would authorize unlicensed television band devices (“TVBDs”) to make use of "unoccupied" parts of current television channels.  TVBDs would have to protect all television stations, and related operations, from any interference.  To do so, TVBDs would have to regularly check TV band databases, and based on information contained there, not operate in a way that could affect television. 

Many of those rules and procedures under which TVBDs must protect television operations from interference are technical in nature.  As general matter, TVBDs would not have to protect unlicensed wireless microphones from interference.  

Many tens of thousands (or more) of wireless microphones currently in use are unlicensed by the FCC, using unoccupied parts of current television channels.  As the FCC noted in its White Spaces Order, new TVBDs would cause interference to existing wireless microphones.  Such interference could be rare or sporadic in nature, depending on circumstances, possibly rendering wireless microphones unusable brief periods of time, intermittently, or perhaps for far longer.  During the past few years, APAP and other organizations have urged the FCC to protect users of wireless microphones from interference from TVBDs. 

In its White Spaces Order, the FCC specifically recognized the plight of wireless microphone users and offered specific, but far from complete, protections. 

Interference Protections for Wireless Microphones


The FCC has limited the channels available for TVBDs in various ways. Importantly, the FCC will reserve two channels nationwide for the exclusive use of unlicensed wireless microphones. The two reserved channels will vary by market or location. In most cases, the reserved channels will be adjacent to or near channel 37. Using currently available technology, the FCC believes that a single television channel will permit the simultaneous use of 6-8 wireless microphones without interference among them. Therefore, the two reserved channels would allow about 12-16 wireless microphones to operate in a small area. An additional 12-16 wireless microphones could be used successfully on the same two channels if properly screened away to prevent interference, or if far enough apart, probably at least 100 meters, or so. In addition, at any particular location, TVBDs may not use a number of channels due to the protection criteria imposed upon them for protection of various kinds of television operations, so in many places, wireless microphones may operate on channels in addition to the two reserved channels without interference from TVBDs. For example, portable TVBDs will not be permitted to operate on channels 20 and below. Even for channels 21 and higher, TVBDs may be restricted or excluded from operations due to the presence of local television broadcasters. In many locations, wireless microphones may be able to operate on channels unavailable to TVBDs.

Therefore, the FCC believes that a significant amount of interference-free spectrum will be available for wireless microphones. As a result, the FCC generally will not permit unlicensed wireless microphones to register in the TV bands databases. In other words, wireless microphones will not be protected from TVBD interference on channels where those devices may operate. Accordingly, most entities desiring to operate wireless microphones on an unlicensed basis, with protection from potential interference by TVBDs, must use the reserved channels and/or other channels on which TVBDs are prohibited due to television station operations.

The FCC recognized that certain large events or venues may require scores of wireless microphones, and therefore may not be fully accommodated by the two, or maybe more, channels on which TVBDs cannot operate in a given location. As a result, the FCC intends to implement an exception to allow qualifying events or venues to file requests to have other channels registered in the TV bands databases, and thereby, gain interference protection from TVBDs on such specified channels for their wireless microphones. Unlicensed wireless microphones at registered sites will be afforded the same protection from TVBDs as licensed microphones but only on the specific event dates listed in the registration request.

The FCC has not yet implemented the procedures, including the TV band databases, necessary for wireless microphone users to request protection from TVBD interference. When it does establish a process, the FCC anticipates that a performance or sports entity could register an event for additional wireless microphones by submitting a request to the FCC at least 30 days in advance that specifies the particular dates and times for which the microphones would be in actual use. Such requests would be subject to public notice by the FCC and could be challenged. The entity would have to certify that it is was using the reserved channels and all other unlicensed channels that were not available locally for use by TVBDs. An entity could only certify its use of "all available channels" if it would be operating at least 6-8 wireless microphones on each of those channels. The FCC would sanction entities that sought additional channels improperly.

What To Do Now?

If an organization's use of wireless microphones is not especially important, is not "mission-critical," then doing nothing for now makes sense.  It will be some time before TVBDs become common.  When they do, if the occasional bout of static, lost communications, or other interference, affecting wireless microphone use is not especially troublesome, then waiting to take action would be smart.  Years from now when it is time to buy new wireless microphones, efficient and compliant equipment could be purchased then.

If reliable wireless microphone use is important or essential, then users need to determine immediately on what frequencies their microphones operate.  They also need to pay close attention to developments in the FCC's ongoing proceedings in order to know when to come into compliance with the White Spaces Order, which probably is at least months away. 

At that point, each organization would have to determine which two channels are reserved for its wireless microphone use and what, if any, additional channels may be usable and protected from future interference from TVBDs due to local frequency usage and conditions.  If the organization's current equipment can operate on reserved or protected channels in order to meet its wireless microphone needs, then all would be well, at least for some period of time.

Other than some prompt (and likely inexpensive) research into wireless microphone frequencies in use and available, the previous discussion relies on "wait and see."  If feasible for a particular organization, avoiding expenditures for now would be wise.  Even though the terms of the White Spaces Order likely will become binding upon TVBDs and other uses of spectrum, wireless microphone users still face an unsettled future.  For example, the FCC is conducting proceedings specifically considering wireless microphones.  While not highly likely, it is possible that decisions made in that proceeding could affect the interference procedures under the White Spaces Order.  In addition, the FCC is requiring low power television stations to complete a permanent transition to digital operations probably within the next two years, or so (as it required already for full power television in 2009).  That transition could affect the availability of channels for wireless microphones in some locations.  Even more serious, if the FCC and Congress follow-through with tentative plans to reduce the number of television channels nationally, in order to make more spectrum available for wireless broadband use, then there could be drastic changes in the availability of channels for unlicensed wireless microphones.  In short, delaying major expenditures for wireless microphones would be the best course while the regulatory picture comes into better focus, and quite possibly, new or improved technologies become available.

Engineering Questions to Consider

Even though we probably are at least one-to-two years away from TVBDs becoming a real problem for wireless microphone users, engineers should make the following determinations in the near future as first steps to prepare for the eventual threat of interference.

The following should be determined per market or local area:

  • What two channels adjacent, or near, to Channel 37 will be reserved for wireless microphone operations?  (If Channels 36 and 38 are vacant, then they would be the reserved channels.  If one or both are not vacant, then what are the vacant channels nearest to Channel 37?)
  • What are the currently licensed or permitted television channels?
  • Due to the channels determined above, what co- or adjacent channels would exclude TVBDs but be available for use by wireless microphones?
  • In particular, what channels on 20 and below would be available for wireless microphones?
  • What venues will need to use more wireless microphones simultaneously than local available spectrum would permit? (The FCC estimates that approximately 6-8 wireless microphones may be used per channel, with at least 100 meters of separation, using current technology.)
  • How often would such venues make such use of wireless microphones?  Is there, or will there be, a schedule?

The following should be determined per user or venue of wireless microphones:

  • What wireless microphones are in use now or are anticipated in the near future? Please include all wireless microphones including those supplied and operated by event consultants, production companies as well as those owned or rented by venue operators.
  • Are all of these wireless microphones unlicensed devices?
  • If so, on what frequencies do the wireless microphones operate?  Are they adjustable or tunable?  (No microphones should be operated on Channels 52-69.)
  • Can the microphones make use of locally available channels?
  • Is such use sufficient or would additional spectrum be needed?
  • If additional spectrum is needed, how much and on what schedule?
  • Would any particular user, or users, of wireless microphones need a waiver of the FCC restrictions or have good grounds to enter the databases for protection from TVBDs?

If reliable wireless microphone use is important or essential, then users need to consider and answer these questions promptly.  Many of these questions are relevant to most or all users of wireless microphones in any local area because presenters in the same markets or local areas are very likely to be subject to the same constraints on their use of wireless microphones.  They could pool their resources and share costs.  Local performance organizations could work together to retain assistance in determining the availability of channels for their wireless microphone use.

If Wireless Microphone Needs Are Great

On the other hand, if an organization has mission-critical wireless microphone needs and cannot risk interference to their use, then it should take the following steps in the near term.

  • Determine what frequencies/channels it currently is using.
  • As soon as possible, determine what channels will be protected in its local area.
  • Determine if its current wireless microphones can operate in locally protected channels.
  • If not, be prepared to register additional channels with the FCC on an as-needed basis, as often as necessary, and not less than 30 days in advance of any particular need.
  • If the strategies listed above would not be sufficient, seek one or more waivers from the FCC, with as much lead-time as possible.
  • Keep careful track of continuing regulatory developments by staying in touch with APAP.

Presenters in the same markets or local areas are very likely to be subject to the same constraints on their use of wireless microphones.  For example, they would be able to use the same reserved channels, and probably, other channels in which TVBDs could not operate.  Thus, local performance organizations could work together to retain assistance in determining the availability of channels for their wireless microphone use.

On January 22nd, 2010 the FCC issued its Final Report and Order regarding the removal of wireless microphones from the 700 MHz band (TV channels 52-69). The FCC also adopted an early clearing mechanism permitting public safety or commercial licensees commencing operations in the 700 MHz Band before June 12 to require wireless microphone users to cease co-channel operations upon 60 days prior notice. The FCC said it had taken this action to "...ensure that public safety and commercial licensees can operate in the 700 MHz Band without interference, while providing entities currently operating wireless microphones in the band with an opportunity to relocate to other bands." A link to the FCC decision can be reviewed here. In coordination with the FCC, APAP issued a fact sheet to guide users on vacating the 700 MHz band.

Note: If a microphone does not operate on frequencies within the 700 MHz band, no action is required.

The Commission posted consumer publications to the Operation of Wireless Mics in 700 MHz Band - FCC Publications section of its Operation of Wireless Mics in 700 MHz Band web site informing the public of these facts. The Commission also published a list of affected microphones at Operation of Wireless Mics in 700 MHz Band - Manufacturers and compiled a Frequently Asked Questions list.

The Commission issued a Further Notice of Proposed Rulemaking focusing on the question of how much regulatory protection wireless microphones will receive from TVBDs (TV band devices). The Commission proposed making most wireless microphone use unlicensed under Part 15 of FCC regulations, which means that wireless microphones will directly compete with TVBDs for available frequencies. A smaller number of users may be licensed under Part 74 of FCC regulations. Licensed users will have access to a database in which they can enter the dates and times of their events using wireless microphones and receive protection from TVBDs.

On March 1, 2010, APAP filed comments in response to the ongoing wireless microphone FCC regulatory proceedings.

APAP’s comments to the FCC (PDF)

On March 23, 2010, APAP filed “reply-comments” in response to the ongoing wireless microphone FCC regulatory proceedings.

APAP’s reply- comments to the FCC (PDF)

Part 74 licensees must:

  • Coordinate frequencies with other Part 74 licensees
  • Avoid TV broadcast and land mobile radio frequencies
  • Keep TV Bands Database entries up to date so that frequencies are protected only during times of actual use. Frequencies will be available to TVBDs when not in use by wireless microphones.
  • Provide all necessary information to the database

Necessary database information includes:

  • Name and contact information
  • Coordinates in latitude and longitude for the location where the wireless microphones will be used (GPS or Google Earth might be useful for this)
  • Specific channels being used
  • Specific dates and times when the wireless microphones will be in use


If there is any additional information that would be helpful or if you have further questions, please contact Emily Travis at APAP or the FCC Consumer Hotline at 1-888-CALL-FCC.